1. Field of the Invention
The present invention relates to a method of manufacturing a lithium silicate-based high-temperature dry sorbent for removing carbon dioxide and a high-temperature dry carbon dioxide sorbent, and particularly, to a method of manufacturing a high-temperature dry carbon dioxide sorbent having excellent capture capacity and reproducibility to remove carbon dioxide released from a power plant or a steel mill and a high-temperature dry carbon dioxide sorbent.
2. Discussion of Related Art
Gases including a vapor, cloud, carbon dioxide, methane, nitrous oxide, ozone, and fluoride compounds (HFC, PFC, ClFC, and SF6) are green house gases affecting climatic changes, and particularly, among these gases, carbon dioxide, methane, nitrous oxide, HFC, PFC and SF6 correspond to six restricted gases. Usually, carbon dioxide is a gas exhausted to an air due to combustion of fossil fuel, and known as a gas having the largest influence on the climatic changes.
As a method for recovering/storing carbon dioxide, an absorption method, a film separation method using gas separation, or an adsorption method using a zeolite adsorbent is known. However, such a method has a high recovery cost due to high energy consumption and is difficult to treat a large amount of carbon dioxide. Recently, a study on a method of capturing carbon dioxide using a dry renewable sorbent is progressing.
Lithium silicate known as a dry carbon dioxide sorbent at a high temperature is degraded in carbon dioxide capture capacity in a long-term use because of grain growth occurring in regeneration of carbon dioxide. In Japanese Laid-Open Patent No. 2003-62965, to compensate such a disadvantage, an alkali metal carbonate and aluminum oxide or an aluminum compound are added after lithium silicate is prepared. However, this method has a complicated manufacturing process which is performed in two steps including preparing lithium silicate by baking (firing) lithium carbonate and silica at approximately 700° C., and additionally adding an alkali metal carbonate and aluminum oxide or an aluminum compound.
In addition, the lithium silicate exhibits a high carbon dioxide capture capacity (under 100 vol % of carbon dioxide) of 24 to 28 wt % at 500 to 550° C. While the lithium silicate has a high carbon dioxide capture capacity, it has a low capture rate and is degraded in capture capacity when continuously used.